This invention relates generally to an indication element driving device utilizing a mechanical flywheel effect, and more particularly to a device which is capable of carrying out, on one hand, a high-speed tuning operation through the positive use of a rotating inertial force of a flywheel which is rotated at a high speed with speeded up a rotation of a tuning control shaft and, on the other hand, a fine tuning operation by subjecting the rotation of said tuning control knob to speed reduction thereby to move an indicator pointer through a very small distance.
As an indication element driving device incorporated into a tuning apparatus in an audio instrument such as a radio receiver there has been known a device utilizing the rotating inertial force of a flywheel. In devices of this type, when the tuning shaft is given a sharp spin, the flywheel starts an inertial rotation. Due to the rotating inertial force of the flywheel, an indication needle or a pointer continues to shift, even after the tuning shaft is released, and moves smoothly across substantially the whole of the dial reading area. Accordingly, this device shows good-operability, particularly in the case where the indication pointer is moved rapidly over a relatively long distance.
The indication element driving device of this type known heretofore is of an arrangement in which a flywheel is directly secured to a tuning control shaft. In this arrangement, the flywheel is adapted to rotate unitarily with the tuning shaft and at the same speed as the tuning shaft, that is, at a relatively slow speed. For this reason, a flywheel of fairly large size is necessary in order to obtain a required inertial force. Accordingly, the above described device has been accompanied by difficulties such that the device becomes bulky and of large weight and therefore cannot be applied to the equipment required to be of small size and of light-weight. Moreover, the above described device is disadvantageous since a fine tuning operation is relatively difficult.